Thunderbird Community Forum

I am a bit of a noob, and probably out of my depth, so please bear with me. It also is a bit of a confusing situation so I hope that I can explain it clearly.

A while ago, Thunderbird stopped working. Whenever I tried starting it up, I got an error message saying that Thunderbird wasn't responding. I thought there might be a problem with some update so I decided that I would reinstall the program. As I went to back up my profile, I found out that there were actually two profile folders where in the past I would only find one. I chose to back up both, and procede with de- and re-installing Thunderbird. After doing so I tried to integrate the old profiles back into the new installation. At first, I chose the largest of the to profile maps and copied it where I found it before the re-installation. I created a new profile using the old profile folder through the User Profile menu. This seemed to work! However, I noticed something. I have two e-mail accounts running in this profile. One IMAP and one POP. I noticed that the POP account was missing about a years worth of old e-mails. As if it stopped saving them at some point. I figured they must be in the other profile folder I found before the re-installation. I tried creating a new profile with this profile but when starting up Thunderbird afterwards I once again got the 'Thunderbird isn't responding' message. So I reverted back to the first profile I made, the one with the missing e-mails. Appart from those e-mails, it seemed to be working well. To get back what was missing, I tried copying the files in the "inbox.sbd" of the back up that wasn't responding into the back up that was responding, thinking that if it messed something up, I could just CTRL + Z my way out of trouble. It seemed that there were three locations in the functioning back up that I could copy the files into, each having the server name of the e-mail account that I was missing e-mails from. I tried copying the files in each of them, each time removing the files through 'undo' before trying the next location. As this seemed unsuccesfull I tried restarting Thunderbird again (having removed the copied files from all locations) which resulted in the following error message:

In a pink screen that I have never seen before. After this I tried removing all profiles and starting again with a fresh copy of the backed up profile folder as I figured I might have accidentally changed something in the profile folder I was using. This however keeps giving the same error message.

Clearly, I messed something up. But I don't know what. Can anybody help? One last thing I noticed that in the 'Mail' folder within the profile folder, there where three folders with the server name before, now there is only one. I guess this is a clue?

All help is welcome!

Copilot has prepared a message for me: Subject: Thunderbird always loads corrupted profile and ignores new profiles

Message:

Thunderbird is stuck loading the same corrupted profile and always shows the welcome screen, even when I create new profiles.

I used the Profile Manager via thunderbird.exe -p and created new profiles (“Clean” and “Clean2”). Both profile folders exist in %APPDATA%\Thunderbird\Profiles. However, Thunderbird still launches the same original profile every time.

Even when I select “Clean2” in the Profile Manager (with “Use the selected profile without asking” unchecked), Thunderbird ignores the selection and loads the old profile. Safe Mode (thunderbird.exe -safe-mode) also does not disable the welcome module.

This appears to be a profiles.ini corruption or a profile lock issue, because Thunderbird is not switching profiles even though the Profile Manager shows the correct selection.

Could you advise how to repair or reset the profile configuration so Thunderbird will actually load a new profile?

Thank you.

06 May 2026 USA Just to inform users:

All mailboxes and all mail in profile are catastrophically and irretrievably deleted when I: 1. Change the location of the profile folder. 2. Make appropriate change in profiles.ini reflecting the location change. 3. Launch Thunderbird in Offline Mode (launching in OFFLINE mode is the fatal event). 4. Mailboxes will appear during this one launched session

    but

5. If Thunderbird is closed while still OFFLINE, then a re-launch of Thunderbird in any state will reveal

     that all mailboxes and all mail have been deleted.

All mailboxes, and of course, all mail in the profile are catastrophically and irretrievably deleted. I was lucky that I made a backup before changing profile location.

The deletion of mail and mailboxes occur at the close of Thunderbird's OFFLINE state. An examination of the profile folder indicates the destruction has occurred upon closing of Thunderbird in OFFLINE state.

It is not the re-launch of Thunderbird that causes the catastrophic deletion. The deletion occurred when Thunderbird was closed in its OFFLINE state.

To successfully change the profile location I must: 1. Make the change to profile location. 2. Make the appropriate change to profiles.ini 3. BE SURE to make the FIRST LAUNCH of Thunderbird in ONLINE mode--ONLINE only. 4. Once 1,2,3 are done, then Thunderbird does not corrupt the profile folder.

Conditions that MIGHT make my configuration uniquely affected: 1. I use Proton Mail Bridge in conjunction with Thunderbird. 2. My Profile folder is on a network share that is letter-mapped in Windows. 3. I have about 10 email addresses in Thunderbird that are Outlook IMAP, Gmail IMAP, and of course, Proton Mail.

I've been using Thunderbird a couple of years in this configuration with no problems. I just decided to rename my profile. So, this is my first discovery of the problem.

Maybe a red herring: I was in the middle of doing a Documents folder backup when I decided to open Thunderbird for some reason. Got an Unable to Load Profile type of message. And my attempts at a fix seem to just send me further down a rabbit hole. I started out by renaming my profile.ini file, but I really didn't know what the heck I was doing and possibly caused more harm than good. Then I tried to find my profile file/folder itself, using the Thunderbird > Troubleshooting > Profile Folder path and doing an import from inside TBird but that ended up with various problems such as drilling down to the profile folder from within TBird but then when I clicked Select Folder in Thunderbird, that didn't trigger any sort of import.

I also spent a good deal of time trying to find my AppData folder, finally being able to view it (a hidden folder, apparently), and saw several recently-dated profile types of folders, but again, I couldn't manage to "hook up" any of those folder/files from starting inside TBird and selecting Import... I ended up just stuck inside a folder, not triggering any Importing activity.

Finally I found a profile folder (5yed...) at a higher level on my PC than inside that long AppData Roaming Thunderbird path. THIS profile was inside: D:\DOCS\Thunderbird\Profiles

Now THAT folder I managed to get an Import to trigger. But the result was an Error Message telling me to go find my Error Console. Can you please see the attached Error Code display screengrab and tell me there's hope that this was at least the right file but just poor results that I can fix somehow???

The following is my copy/paste of the text I see in the Error Console display that's in my screengrab after trying to import the above 5yed... profile, in case it helps you see it better:

1765349209272 addons.xpi WARN Checking C:\Program Files (x86)\Mozilla Thunderbird\distribution\extensions for addons WebGL context was lost. 2 Troubleshoot.sys.mjs:727:17 Content-Security-Policy: This site (https://www.mozilla.org) has a Report-Only policy without a report-uri directive nor a report-to directive. CSP will not block and cannot report violations of this policy. thunderbird downloadable font: Glyph bbox was incorrect (glyph ids 441 459 695) (font-family: "Open Sans" style:normal weight:700 stretch:100 src index:0) source: https://updates.thunderbird.net/media/fonts/opensans-bold.woff2 downloadable font: Glyph bbox was incorrect (glyph ids 459) (font-family: "Open Sans" style:normal weight:400 stretch:100 src index:0) source: https://updates.thunderbird.net/media/fonts/opensans-regular.woff2 Uncaught (in promise) NS_ERROR_FILE_NOT_FOUND: Component returned failure code: 0x80520012 (NS_ERROR_FILE_NOT_FOUND) [nsIFile.copyTo]

   _recursivelyCopyMsgFolder resource:///modules/ThunderbirdProfileImporter.sys.mjs:652
   _recursivelyCopyMsgFolder resource:///modules/ThunderbirdProfileImporter.sys.mjs:661
   _mergeLocalFolders resource:///modules/ThunderbirdProfileImporter.sys.mjs:634
   _importServersAndAccounts resource:///modules/ThunderbirdProfileImporter.sys.mjs:243

ThunderbirdProfileImporter.sys.mjs:652

Also attached below are also:

• a screengrab of a set of profiles I found, but when I drilled down to them from within TBird's Import selections and clicked Select Folder, as far as I got was an open folder, or something like that.
• Thunderbird's Troubleshooting Info "Profile Folder" path.
• Message telling me to see the Error Console. The message appeared right after I tried importing the profile that's stated in TBird's Troubleshooting Info "Profile Folder" path.

Here's the copy/paste of the Error Console message display after my try at importing the profile that is in the path that TBird's Troubleshooting Info page "Profile Folder" states (maybe it's the same as my 5yed...profile import try's Error Console display, dunno:

1765353636640 addons.xpi WARN Checking C:\Program Files (x86)\Mozilla Thunderbird\distribution\extensions for addons Content-Security-Policy: This site (https://www.mozilla.org) has a Report-Only policy without a report-uri directive nor a report-to directive. CSP will not block and cannot report violations of this policy. thunderbird WebGL context was lost. 2 Troubleshoot.sys.mjs:727:17 downloadable font: Glyph bbox was incorrect (glyph ids 441 459 695) (font-family: "Open Sans" style:normal weight:700 stretch:100 src index:0) source: https://updates.thunderbird.net/media/fonts/opensans-bold.woff2 downloadable font: Glyph bbox was incorrect (glyph ids 459) (font-family: "Open Sans" style:normal weight:400 stretch:100 src index:0) source: https://updates.thunderbird.net/media/fonts/opensans-regular.woff2 Uncaught (in promise) NS_ERROR_FILE_NOT_FOUND: Component returned failure code: 0x80520012 (NS_ERROR_FILE_NOT_FOUND) [nsIFile.copyTo]

   _recursivelyCopyMsgFolder resource:///modules/ThunderbirdProfileImporter.sys.mjs:652
   _recursivelyCopyMsgFolder resource:///modules/ThunderbirdProfileImporter.sys.mjs:661
   _mergeLocalFolders resource:///modules/ThunderbirdProfileImporter.sys.mjs:634
   _importServersAndAccounts resource:///modules/ThunderbirdProfileImporter.sys.mjs:243

ThunderbirdProfileImporter.sys.mjs:652

Thanks for any help in getting through this.

Updating the old question I have as I have attached more detailed information.

Same profile existing in Thunderbird and one is taking up 100 GB space. The Cloud station folder was setup before, and I have no history of it, it might be a shared drive, I don't know why it takes up 100 gb of space and it has a same copy on the Users profile with lesser storage around 33 gb. Can somebody help, i'm not deleting any profiles cause I don't want to accidentally delete emails and the profile has emails older than 2020.

I need to free up some space on this machine without losing the emails as disk is getting full because of this problem.

Attached screenshots

I have been using Thunderbird since its first incarnation. I currently monitor (some for non-profits, some my own) five email accounts in Thunderbird. They are all IMAP accounts. However, my own main account also has an extensive system of local folders that adds up to about 12GB of data, and probably over 100 folders (don't ask; it was necessary until I retired last year, but I need to keep all of those saved emails, as I still access them frequently).

I've searched the forums and have found good information on moving Tbird to a new computer, but that's not what I'm looking for. Chances are what I need is here, and I've missed it, so please forgive if I'm rehashing old questions.

Currently, my Thunderbird profile and folders are stored on my C: drive, as is the default. I have been manually backing them up several times a week (for years) to OneDrive, because I can't afford to lose everything if my laptop decides to bite the dust. Using that method, I've successfully moved the setup to a new computer several times. I'm not sure why simply redirecting the setup to a different location on the same system has been a bugbear for me. ::smile::

It would be much less labor-intensive if I can simply point Thunderbird to the OneDrive files so they are always up-to-date and "there," should I need to make a computer change again.

Note, that I am not looking to access the Tbird installation with multiple computers.

I have tried (and failed) to do this in the past. Either my emails are not there, my address books are missing, or a variety of other issues that indicate an incomplete move.

I'm ready to give it another shot, and I appreciate your time and help.

[Profile2] Name=default-release IsRelative=1 Path=Profiles/dzsmofpl.default-release [Profile1] Name=default IsRelative=1 Path=Profiles/g92ibtwu.default Default=1 [Profile0] Name=default-esr IsRelative=1 Path=Profiles/2i2jua4d.default-esr [General] StartWithLastProfile=1 Version=2 [Install712DAF5A23ABECDC] Default=Profiles/2i2jua4d.default-esr Locked=1 [InstallFEE05927A5AEB8AE] Default=Profiles/dzsmofpl.default-release Locked=1

I recently moved my TB to a new PC desktop, and TB is working fine. But I see that my local archive folder is gone from both the new and the old PC, as well as my NSTMP folder. Could someone help me locate them?

thanks